FIG. 1 depicts a schematic diagram of a portion of a typical wireless communications system in the prior art. Such a system provides wireless telecommunications service to a number of wireless terminals (e.g. wireless terminals 101-1 through 103-1) that are situated within a geographic region.
The heart of a typical wireless telecommunications system is Wireless Switching Center ("WSC") 120, which may also be known as a Mobile Switching Center ("MSC") or a Mobile Telephone Switching Office ("MTSO"). Typically, WSC 120 is commented to a plurality of base stations (e.g., base stations 103-1 through 103-5) that are dispersed throughout the geographic area serviced by the system. Additionally, WSC 120 is connected to local-and toll-offices (e.g., local-office 130, local-office 138 and toll-office 140). WSC 120 is responsible for, among other things, establishing and maintaining calls between wireless terminals and between a wireless terminal and a wireline terminal, which is connected to the system via the local and/or long-distance networks.
The geographic area serviced by a wireless telecommunications system is partitioned into a number of spatially-distinct areas called "cells." As depicted in FIG. 1, each cell is schematically represented by a hexagon; in practice, however, each cell usually has an irreguilar shape that depends on terrain topography. Typically, each cell contains a base station, which comprises radios and antennae that the base station uses to communicate with the wireless terminals in that cell and also comprises the transmission equipment that the base station uses to communicate with WSC 120.
For example, when wireless terminal 101-1 desires to communicate with wireless terminal 101-2, wireless terminal 101-1 transmits the desired information to base station 103-1, which relays the information to WSC 120. Upon receiving the information, and with the knowledge that it is intended for wireless terminal 101-2, WSC 120 then returns the information back to base station 103-1, which relays the information, via radio, to wireless terminal 101-2.
The manner in which the information received from WSC 120 is processed within base station 103-1 is depicted in FIG. 2. Such information is transmitted from WSC 120 to base station 103-1 as multiplexed signal 202. Such a signal comprises a multiplicity of constituent signals, which, in the context of present discussion, are RF carrier signals. Each one of such constituent RF carrier signals differs from all other of such signals in accordance with a particular multiplexing scheme used (e.g., time-division-multiplexing, frequency-division-multiplexing, code-division-multiplexing, etc.).
When received by base station 103-1, signal 202 is de-multiplexed into its constituent RF carrier signals 202.sub.i,i=l,N in demultiplexer 204. Each one of the N constituent RF carrier signals is routed to a corresponding one of N radios 206.sub.i,i=l,N. Each radio 206 is operable to modulate a message signal onto the one constituent signal 202.sub.i that it receives in accordance with a particular modulation scheme (e.g., time-division-multiple-access, code-division-multiple-access, etc.). A modulated RF carrier signal 208.sub.i generated by each radio is delivered to summing device 210 wherein such modulated carrier signals are summed to generate multicarrier RF signal 212.
As the modulated RF carrier signals 208.sub.i generated by the radios are very low power signals, multicarrier RF signal 212 must be routed to amplifier 214, typically a feedforward multicarrier linear RF power amplifier ("FMLRF power amp"), to boost signal strength for transmission from the base station to various wireless terminals, such as 101-2. A FMLRF power amp can usually amplify all RF carrier signals in use within a given cell. The design and operation of such amplifiers are familiar to those skilled in the art. See, for example. U.S. Pat. No. 5,304,945, incorporated by reference herein.
Within FMLRF power amp 214, multicarrier RF signal 212 is divided by splitter 216 into J equal power signals 212.sub.i and delivered to J identical amplifier modules 218.sub.i. Each one of the signals 212.sub.i is amplified to a set output power in the amplifier modules. J amplified signals 220.sub.i from the amplifier modules are combined to form modulated multicarrier RF signal 224 in combiner 222. The signal 224 is routed to antenna 226 for transmission, such as to wireless terminal 101-2.
Ever-increasing wireless traffic results in a need to increase the calling capacity of such wireless systems. One way to increase calling capacity is to increase the number of cells within a given geographic area. Such an increase results in smaller cells, and, of course, more base stations. Increasing the number of cells results in a decrease in signal transmission power requirements (due to a smaller coverage area), thus enabling use of smaller, lower power FMLRF power amps.
Past splitter and combiner designs for conventional high power FMLRF power amps have utilized cavities of a specific size and geometry well-matched to such larger FMLRF power amps. With the decreasing size requirements of such power amps, a new more compact design for a power splitter and power combiner are needed.